The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.
In multi-cylinder engines for which a plurality of fuel injectors are required, it is common to use a fuel rail assembly to supply fuel to the fuel injectors. Typically, the fuel rail assembly comprises a rigid fuel rail, which comprises a manifold adapted for connection to a fuel supply, and a plurality of fuel injectors rigidly connected to the fuel rail. With this arrangement, the fuel rail provides a mounting for the fuel injectors and supplies fuel to the injectors.
For indirect or manifold injection applications, the fuel injectors deliver fuel at some point before the intake valve, typically into an inlet manifold. With this delivery arrangement, the fuel injectors typically communicate with injection ports in the inlet manifold.
There is a need for the location of the fuel injectors in a fuel rail assembly to match the spacing and orientation between injection ports. Unless there is precision in the positioning of the fuel injectors in the fuel rail assembly, there can be misalignment between at least some of the extensions on the fuel injectors and the injection ports into which the extensions need to locate. Any such misalignment can present a difficulty to the installation and sealing of the fuel injector assembly on an engine.
The invention is particularly applicable to liquid phase injection (LPI) of gaseous fuels such as LPG, and in particular to LPI systems for multi-cylinder engines.
For the LPI process it is necessary to deliver liquefied gaseous fuel to a fuel injector in the liquid phase. The requirement to maintain the liquid phase of the liquefied gaseous fuel necessitates that the fuel be maintained under pressure.
During the delivery process there is a phase change at the outlet of the injector, which can lead to rapid cooling and, consequently, formation of ice on the tip of the injector nozzle. The formation of ice on the injector nozzle is disadvantageous as it can lead to deterioration in the performance of the nozzle.
There have been various strategies proposed to address the issue of icing of an injector nozzle.
For indirect injection applications, one known strategy involves configuring the fuel injector as an injector body and a nozzle portion, with the nozzle portion providing an extension from the nozzle body to terminate at the nozzle tip. The extension is adapted to be received in an injection socket which is typically an intake manifold injector bore. The extension defines a delivery path which extends from a receiving chamber within the injector body and along which the gaseous fuel can be conveyed to the nozzle tip for delivery into the injection socket.
The extension comprises an inner tube defining the fuel delivery path terminating at the nozzle tip and a casing surrounding the inner tube, the casing presenting an end face at the tip of the nozzle portion.
The extension provides the tip of the nozzle and is adapted to provide thermal insulation to prevent heat loss during passage of the liquefied gaseous fuel to the outlet. Further, the extension is adapted to collect heat from the engine, thereby contributing to a reduction in thermal losses during passage of the liquefied gaseous fuel to the outlet. Additionally, heat so collected may assist in the reduction of icing at the nozzle outlet.
Typically, for LPI indirect injection applications, side feed fuel injectors are used.
It is against this background, and the problems and difficulties associated therewith, that the present invention has been developed.